1. What is CFM Calculation?

CFM (Cubic Feet per Minute) is a measurement of airflow volume. This calculation determines the required airflow for proper ventilation based on room size and desired air changes per hour.

2. How Does the Calculator Work?

The calculator uses the CFM equation:

Where:

• \( Volume \) — Room volume in cubic feet (ft³)
• \( ACH \) — Air changes per hour (1/h)
• 60 — Conversion factor from hours to minutes

Explanation: The equation converts the total volume of air that needs to be changed per hour into the required airflow per minute.

3. Importance of CFM Calculation

Details: Proper CFM calculation is essential for designing HVAC systems, ensuring adequate ventilation, maintaining indoor air quality, and meeting building code requirements.

4. Using the Calculator

Tips: Enter room volume in cubic feet and desired air changes per hour. All values must be valid (volume > 0, ACH > 0).

5. Frequently Asked Questions (FAQ)

Q1: What is a typical ACH value for residential rooms?
A: Living rooms typically need 4-6 ACH, kitchens 7-8 ACH, and bathrooms 8-10 ACH, but requirements vary by usage and local codes.

Q2: How do I calculate room volume?
A: Multiply room length × width × height in feet. For irregular rooms, divide into regular shapes and sum the volumes.

Q3: What's the difference between CFM and ACH?
A: CFM measures airflow rate, while ACH measures how often the total air volume is replaced per hour. CFM is flow rate, ACH is frequency.

Q4: When is higher CFM needed?
A: Higher CFM is needed in spaces with more occupants, higher heat loads, or greater pollutant generation (like kitchens or labs).

Q5: How does CFM relate to fan selection?
A: Fans should be selected to meet or exceed the calculated CFM requirements while accounting for ductwork resistance (static pressure).